This invention relates to helmets and more particularly to a visored helmet that protects the wearer from trauma and also provides a source of filtered air for respiration.
Hard hats are worn by users to protect the head from injury. The hats may also have transparent visors to further protect the face and eyes. Users are known to remove the hats when they become overheated and when the visors become fogged up, thereby endangering the user and possibly exposing an employer to liability.
Furthermore, many workers are exposed to harmful dusts and fumes. They may be provided with various types of filter masks or respirators to supply respiratory air from which such noxious materials have been removed. These may be awkward to use with a visored helmet and may require so much inspiratory effort to suck air through the filter that they may be put aside when they should be used. For workers with emphysema, any increase in inspiratory effort is overwhelming.
U.S. Pat. Nos. 3,881,478 issued May 6, 1975 to Rosendahl et al and 735,959 issued Aug. 11, 1903 to Folkmar disclose head coverings providing respiratory air from an external air supply through a duct. The duct restricts worker's movement and pulls on the head covering.
U.S. Pat. Nos. 3,963,021 issued Jun. 15, 1976 to Bancroft; 4,136,688 issued Jan. 30, 1979 to Gorman; 4,133,308 issued Jan. 9, 1979 to Lowe et al.; 4,280,491 issued Jan. 28, 1981 to Berg et al.; and 4,730,612 issued Mar. 15, 1988 to Dampney teach visored helmets containing rear mounted motorized fans in a duct forcing filtered air over the head and down to the user's face. The small diameter of the fans dictated by the duct size limits the air flow and requires high motor speed. The high motor speed causes noise problems and the limited air flow requires elaborate face sealing mechanisms on the visor to ensure that enough air flows past the nose and mouth that unfiltered air is not inhaled. U.S. Pat. No. 4,744,106 issued May 17, 1988 to Wang teaches a hard hat with a fan in a hinged fan element fitting into an aperture in the crown for blowing air over the head to cool it. A retractible curtain covers the open space in case of rain. The device does not provide filtered air for respiration, nor does it provide the complete head covering to prevent injury from small objects that would penetrate the air openings as does rain. Furthermore, the motor positioned above the fan blades yields a high center of gravity that is awkward for the active wearer.